How to find the menu [slug] item

Try the name your theme uses when registering the menu:
https://codex.www.ads-software.com/Navigation_Menus#Register_Menus

In this example the slug is ‘header-menu’

function register_my_menu() {
  register_nav_menu('header-menu',__( 'Header Menu' ));

}
add_action( 'init', 'register_my_menu' );

https://codex.www.ads-software.com/Function_Reference/register_nav_menu

Thank you. I appreciate it but I’ve finally figured it out. I just went into my functions.php and look for the register_my_menu and it’s there.